On average, teens who consumed sports and energy drinks at least once a week played more hours of video games, drank more servings of sugar-sweetened beverages and were more likely to have ever smoked cigarettes, compared to those who consumed sports and energy drinks less than once a week.

For example, boys who consumed energy drinks at least once a week spent about four more hours per week playing video games, compared to those who consumed energy drinks less often.

And about 20 percent of boys and girls who frequently consumed energy drinks said they had smoked cigarettes, compared to about 8 percent of those who consumed energy drinks less often.

Boys who consumed sports drinks at least once a week also watched about an hour more TV per week than boys who consumed sports drinks less often.

The findings "are troubling because they may indicate a clustering of problem behaviors among some adolescents," the researchers, wrote in the May/June issue of the Journal of Nutrition Education and Behavior.

However, the study was conducted at one point in time, so the researchers cannot say which came first, the sports and energy drink consumption, or the other unhealthy behaviors.

But the study does show that these behaviors tend to track together, said Dr. Jason Block, an assistant professor of population medicine at Harvard Medical School, who was not involved in the study.

"Based on this study, we can't blame the sports and energy drinks at all," for the higher levels of unhealthy behaviors, Block said. "It's just that adolescents who aren't focused on healthy behaviors are more likely to consume these beverages," Block said.

Block said he is not aware of any evidence suggesting that sports and energy drinks are a gateway to other unhealthy behaviors. Future studies that follow teens over time are needed to determine the reason for the link, the researchers said.

The researchers noted that teens' exposure to TV advertising for energy drinks increased 20 percent between 2009 and 2010.

"It is critical that adolescents and their parents are educated about the potential consequences associated with consuming sports and energy drinks, and that targeted advertising does not continue to encourage them to purchase these beverages," study researcher Nicole Larson, of the University of Minnesota's School of Public Health, told the Journal of Nutrition Education and Behavior in an interview.

The American Academy of Pediatrics says that sports drinks are unnecessary for the average young athlete, and that because the drinks contain sugar, they could contribute to weight gain and tooth decay. However, the AAP also says that drinking a small amount of sport drinks may be appropriate for young athletes who have been vigorously exercising for prolonged periods.

In the new study, teens' sports drink consumption was linked with higher levels of moderate-to-vigorous activity per week, and with a higher percentage of participation in sports, however "it is unlikely that consumption only followed vigorous, prolonged activity as recommended by the AAP," the researchers said.

"Water should instead be promoted as the best option for hydration following physical activity," Larson said.